The present invention relates to the field of graphic image films. More particularly, the present invention provides methods of registering composite graphic images on films as the films are applied to a substrate and kits including films used to form a composite image.
Composite images formed using multiple films with complementary portions of the composite images formed thereon are often used for advertising on, e.g., trucks, signs, and other large surfaces. The images must often be provided as composites using multiple films due to size limitations in the manufacturing and application of the films on which the images are provided, i.e., one film that is large enough to contain the entire image may be impossible to produce and/or apply.
Although film-based graphic images can typically be made in unlimited lengths (particularly when using digital imaging methods), variations during the imaging processes may also introduce errors into the manufactured-length of the images on the films. For example, differences in brake tension during manufacturing can easily cause a difference in manufactured film length of 0.1%. These errors can be accommodated with known manual application techniques using relatively short panels because skilled applicators can adjust the film dimensions during installation. If, however, the films are to be applied to a large surfaces such as a semitrailer that is, e.g., 53 feet (16 meters) long, the errors in the images on two different films may be about 0.5 inches (1.25 centimeters), which is typically unacceptable.
In addition to the dimensional tolerance errors that can be introduced into long films during imaging, very long films are also difficult to handle and apply by conventional techniques. As a result, the complete composite images are typically formed using a number of panels of film that are, e.g., 36 to 48 inches (about 1 to 1.25 meters) wide and 8 to 9 feet (about 2.5 to 3 meters) long. Each panel includes a portion of the composite image and, thus, the panels must be properly aligned with each other to present a high quality composite image to a viewer.
The composite image is formed on the substrate by manually adhering the films to the substrate using, in most cases, a pressure sensitive adhesive. An applicator usually starts at the top of each film and works toward the bottom while removing a liner used to protect the adhesive. The films are laminated to the substrate using manual pressure applied with a squeegee-like device approximately 10 centimeters long. A skilled applicator will stretch or pull each film slightly as it is being applied to maintain registration between the different panels used to form the composite image. Such manual registration helps compensate for any dimensional errors introduced during the imaging processes. Limiting the length of the panels also reduces visible error. The process of aligning and adhering each film is typically, however, labor intensive and requires a high degree of skill on the part of the applicator. Furthermore, the longevity of the resulting composite image can depend on the skill of the applicator in properly adhering the films to the substrate.
The present invention provides methods of forming composite images on a substrate using a plurality of films that are applied and registered with each other under tension. The films may include registration marks distributed along their lengths and those registration marks can be used to vary the tension under which the films are dispensed during application to a substrate.
By detecting the registration marks already applied to a substrate and detecting corresponding registration marks on a film being dispensed and applied to the substrate, registration between the different portions of the composite images on the different films can be maintained over the length of the films to precisely align all sections of the composite image formed by the films. That registration is controlled by varying tension of the film being applied. It may be advantageous to apply all of the films, including the first film, under at least some continuous level of tension to provide the opportunity to control registration of the later-applied films by varying the tension under which the later-applied films are dispensed. For example, a first film may be dispensed and applied at a predetermined tension or stretch. The tension or stretch on successively applied films can then be varied above and/or below the predetermined setpoint of the first film to control registration.
Other advantages of various aspects of the present invention include the ability to form composite images using films that extend continuously and unbroken along the length of the composite image. As a result, the films forming the composite image may overlap in only one direction with no films required to abut each other along the length of the composite image. In some aspects, the films and the composite image they form may have a length of at least about 5 meters or more, at least about 10 meters or more, and, in some instances, at least about 15 meters or more. It may also be advantageous to dispense the films from rolls.
The registration marks on films already applied to the substrate may be covered by later-applied films. With respect to the last film applied to complete the image, the registration marks may be removed before or after application of the last film to the substrate. Other alternatives include the use of registration marks that are invisible to the unaided human eye, or the use of registration marks that are washable after the films are applied to the substrate. Another alternative is the use of registration marks on the liners used to deliver a film including a pressure sensitive adhesive on one surface.
In one aspect, the present invention provides a method of providing a composite image on a substrate by providing a first film on the substrate, the first film including a first portion of the composite image; providing first registration marks distributed along a length of the first film; providing a second film, the second film including second registration marks distributed along a length of the second film and a second portion of the composite image; aligning the second portion of the composite image on the second film with the first portion of the composite image on the first film; dispensing the second film under tension along the length of the second film; detecting the first and second registration marks during the dispensing; varying the tension along the length of the second film based on the detection of the first and second registration marks to register the first and second portions of the composite image along the lengths of the first and second films; and applying the second film to the substrate. It may be preferred to continuously apply the tension under which the second film is dispensed.
In another aspect, the present invention provides a method of providing a composite image on a substrate by providing a first film on the substrate, the first film including visible first registration marks distributed along a length of the first film and a first portion of the composite image; providing a second film, the second film including visible second registration marks distributed along a length of the second film and a second portion of the composite image; aligning the second portion of the composite image on the second film with the first portion of the composite image on the first film; dispensing the second film under tension along the length of the second film; detecting the first and second registration marks during the dispensing; varying the tension along the length of the second film based on the detection of the first and second registration marks to register the first and second portions of the composite image along the lengths of the first and second films; applying the second film to the substrate and the first film such that a portion of the second film is located over the first registration marks on the first film; and removing the second registration marks from the second film.
In another aspect, the present invention provides an image graphic kit including a composite image having a length and a height transverse to the length; a first film including a first portion of the composite image on a major surface of the first film, adhesive on the opposing major surface of the first film, and a pattern of first registration marks distributed in regular intervals along the length of the first film; and a second film including a second portion of the composite image on a major surface of the second film, adhesive on an opposing major surface of the second film, and a pattern of second registration marks distributed in regular intervals along the length of the second film. These and other features and advantages of the present invention are described below in connection with some illustrative embodiments of the invention.